Refill for a writing instrument



FIG. 1 is a perspective view of refill for a writing instrument showing my new design;

FIG. 2 is a front elevation view of FIG. 1;

FIG. 3 is a right side elevation view of FIG. 1;

FIG. 4 is a rear elevation view of FIG. 1;

FIG. 5 is a left side elevation view of FIG. 1;

FIG. 6 is a top plan view of FIG. 1; and,

FIG. 7 is a bottom plan view of FIG. 1.

The broken lines in the drawings illustrate unclaimed portions of the writing instrument and form no part of the claimed design. 

CLAIM The ornamental design for a refill for a writing instrument, as shown and described. 